The formation that occurs when large quantities of magma begin to push through the Earth's mantle and into layers of the crust is called a volcano.

Here's why:

* Magma: Molten rock found beneath the Earth's surface.

* Mantle: The layer of the Earth between the crust and the core.

* Crust: The outermost layer of the Earth.

When magma rises from the mantle, it creates pressure on the surrounding crust. This pressure can eventually cause the crust to fracture and break, allowing the magma to erupt onto the surface. This eruption forms a volcano.